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Flashcards in Toxocology Deck (24):
1

Toxicology

Study of adverse effects of xenobiotic compounds

• including:
- chemical properties
- biological effects,
- Tx

2

Poison

Any substance capable of causing a DELETERIOUS RESPONSE in a
biological system

3

Toxin

Poisons that originate FROM LIVING ORGANISMS

(i.e., zootoxins from
animals, phytotoxins from plants, bacterial toxins)

4

Toxicant

Toxic substances, chemicals produced by HUMAN-MADE activities

5

Factors Determining Toxicity

1. Dose
2. Duration/Frequency of Exposure
3. Route of Exposure
4. Toxicokinetics (ADME)
5. Physiological Factors

6

Dose

AMOUNT of drug, toxin or toxicant that REACHES THE SITE OF ACTION in an animal

7

LD50 vs LC50

??

8

Hormesis

Essential nutrients or non-nutritional toxic substances imparting beneficial effects, but ADVERSE EFFECTS AT HIGH OR LOW DOSES

• Selenium
• Zn

9

Acute Exposure

– Exposure to a chemical for < 24 hrs

– SINGLE DOSE occurring from a single incident
• Iron overdoses in pigs
• Insecticide ingestion in animals

10

Subacute Exposure

– Exposure to a chemical for < 1 month

– Repeated doses
• Dogs eating aflatoxin contaminated food for 4 weeks

11

Subchronic Exposure

Exposure to a chemical for 1 - 3 months

12

Chronic Exposure

Exposure to a chemical for > 3 months to years

13

Why are birds more sensitive to gases?

– Highly efficient at exchanging gases for high oxygen delivery to muscles for flight

– High metabolic rates, small size

– The air breathed is rapidly distributed to tissue

14

Parenteral Routes

1 - IV
2- inhalation
3- IP
4- SQ
5- IM

15

Which parenteral routes pass thru the liver before going to the body?

Intraperiotoneal
• used to experimentally mimic oral exposure

16

What does ADME stand for?

A - absorption
D - distribution
M - metabolism
E - excretion

17

What factors is most important regarding absorption of a toxin/toxicant?

Solubility
- Depends on the degree of ionization @ specific pH value = pKa of drug

18

Non-ionized drugs are ____ soluble?

Lipid soluble

19

Lipophilic toxicants

OP/carbamate insecticides

• Lipophilic

20

Insoluble salts

Barium sulfate = contrast radiography

21

pH of:
- Rumen
- Reticulum
- Omasum
- Abomasum

- Rumen
• 5.4 - 6.8
- Reticulum
• 2
- Omasum
• 5.4 - 6.8
- Abomasum
• 2 - 4

22

Hay containing > 1% nitrate in rumen ---> ...?

Normally the Ruminal flora converts Nitrate --> nitrite --> ammonia to protein

• ↑ Nitrate conversion excess microflora capacity
--> Nitites absorbed in blood
--> oxidized Hb
--> Methemoglobin cannot release O2 to tissues
--> cyanosis + metHb-emia!!

23

How does GI motility affect drugs ADME?

↓ gastric motility / emptying
--> ↑ absorption

24

How can you prevent absorption?

1. Emesis
-- xylazine / apomorphine
2. Activated charcoal + cathartic (accelerate defecation)